Felt



Patented May 10, 1932 UNITED STATES PATENT? OFFICE PHILIP W. GODWISE, F KENMORE, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 CERTAIN-TEE!) PRODUCTS CORPORATION, A CORPORATION OF MARYLAND FELT No Drawing.

tinuation in part of my copending applica tion Serial No. 42,316,, filed July 8, 1925.

The nature of the invention may be best understood by reference to one exemplifica tion. thereof relating to vegetable and wood fibre having novel and advantageous characteristics and to one illustrative use of such In the present exemplification of the invention, vegetable fibre, which is advantageously in the form' of wood chips (pine chips for example) is partially disintegrated by treatment which partially removes or loosens the lignins, resinous and pectic substances which occur withthe bundles of fibre to make up the wood structure. 7 This partial removal or loosening of these encrusting and binding substances preferably does not result in a reduction of the wood to ultimate cellulose fibre nor substantially so, but preserves the bundles of fibres with their characteristic length and strength, rendering them soft and capable of 1 interlacing and felting well. Such partial disintegration of the wood structure may be advantageously effected in the present instance, by cooking the chips under pressure in a relatively weak alkaline solution. To assist in disintegration and to facilitate the action of the alkali onthe wood structure, the wood chips may be given a preliminary treament'which promotes the penetration or impregnation of the wood by the alkaline solution. For example, such preliminary treatment may consist in steaming the wood chips (using one hundred parts of pine chips as a convenient illustration) in a digester for about three-quarters of an hour.

form by the usual'chippingmachine, the chips in such cases being about one inch in length.

The treatment with steam apparently promotes the rapid impregnation of wood with 59 an alkaline solution, which impregnation so that a chemical recovery system may be im- The wood may be provided in convenient chip Application filed August 19, 1926. Serial No. 130,361.

should take place immediately after steaming. Thorough impregnation is obtained by soaking in a solution containing, for example, sodium hydroxide for a period suflicient to effect the desired result.

If desired the above mentioned preliminary steps can be omitted and the proper amount of alkali in suitable solution may be introduced directly into the digester preparatory to the cooking period which will now be described.

The chips are then subjected to an alkaline cook, such as withsodium hydroxide in about seven percent proportion. The amount of alkali is based upon the bone. dry weight of the ohipsthe amount being determined by what is necessary under proper treatment to secure adequate disintegration of the fibre encrusting substances and the desired condition of the fibrebut usually falls within the limits of four .to twelve percent. Sodium hydroxide is preferable as an alkali because of its 'efliciency, yet other chemicals, such as sodium sulphite, sodium carbonate, calcium hydroxide may be. used. However, a low 76 percentage of alkali is important in that it assists in the peculiar disintegration of the wood, and further reduces the chemical cost necessary. While any wood which will respond to treatment-to secure the desired fibre properties may be used coniferous woods such as pine, fir, hemlock, cedar and spruce, are advantageous because of low cost and. character of fibre produced.

The chips are cooked in a digester under steam pressure of about pounds per. square inch pressure and at a temperature of about C. Where the chips are, not subjected to the preliminary softening and impre nation treatments, the time consumed in 000 ing is somewhatlonger-from six to twelve hours-and the alkaline concentration in the digester per 100 parts of wood) should be from 4 to 10 parts weight of sodium hydroxide in about 300 parts by weight of water. If the chips are given a preliminary steaming the time consumed in cooking is lessened by several hours.

After the cooking has been carried to the proper point, the chips are removed from the digester and washed. They are now in such a state that they may be reduced to the roper fibre condition by mechanical shred- 5 ing, washing, and beating with water. The shredding is conducted so that the bundles are separated from each other, without the bundles themselves being shredded to any material extent. While other suitable means may be employed, I have found a swin hammer pulverizer most eflicient, whereby the fibres are beaten in air, with the swing hammers setting up an air circulation to remove the beaten bundles. The degree of shredding is regulated by the exit door of the machine.

The resulting product has peculiar and distinctive characteristics, andis suited for many uses in which wood fibre has not heretofore been adapted or satisfactory. The

converts the long sliver-like formations of the wood into irregular composite fibre bundles in which the fibres are held together only sufliciently to give the bundle the desired length and stren h but not firmly enough to impair its flexib' 'ty and softness nor to interfere with its intertwining and felting characteristics. Contributing to the latter characteristics are the numerous loose and free ends of the individual fibres or groups of fibres which pro'ect from the body of the fibre bundles. lVood fibre product is a fibrous mass containing long slender fibrous aggregates, each of which contain a various number of fibres. These ag egates vary from the length of an individual fibre to bundles of these fibres some of which are about one and one-half inches in length. The average length of a bundle is approximately one-half inch with the average width varying from that of an individual fibre to one sixtyfourth of an inch. There will be a certain proportion of short fibres which intermingle with and bind the bundles together.

be put to any desired use. By way of illustration, it may be run directly into an ordinary felt machine, such as the Fourdrinier or cylinder type, and manufactured into a strong, soft and porous felt. Contributing to the porosity of the sheet is the characteristic coarseness of the fibre bundles which will strongly intertwine and felt without be-- partial disintegration of the wood structure After the beating treatment, the stock may Among other characteristics,- the felt is re-' The distinctive properties of the felt are manifest not only in its absorptive capacity but in rapidity of absorption. Contributing thereto are the characteristic porosity of the felt and the ca illarity of the bundles of fibres largely ma ing up the felt,the capillarity probably being produced by the capillary spaces between, .within and around the loosened fibres left by the removal or partial removal of the encrusting substances asso- I gree of porosity desired for the felt. I have found medium weight felt composed of substantially wood stock and 25% waste stock to be well adapted for ordinary purposes. It is to be understood, however, that the waste stock is not an essential ingredient, and, if used, can be used in any proportion desired. The absorptiveness may also be regulated to some extent by the degree and duration of compression to which the felt web is subjected in the felt machine, although this novel wood fibre, unlike other fibre stock, has the ability to intertwine and felt naturally without material compression, thereby making it possible to make a very open and porous felt.

Obviously the invention is not limited to the details of the exemplification thereof herein described, since these may be variously modified. Moreover it is not indispensable.

that all features of the invention be used conjointly since various features may be advantageously employed in different combinations and subcombinations.

Having, described one embodiment of my invention, I claim:

1. The process of producing a fibre product from wood which consists in modifying by incomplete chemical treatment the substances naturally encrusting and binding the fibres of.

the wood while not-completely-releasing in said treatment the fibres from each other, and subdividing the wood for the most part into bundles of long fibres maintaining approximately the natural arrangement of the fibres with respect to each other in the bundles.

2. The process of producing a fibre product which consists in the partial disintegration of wood by cooking under pressure in an alkaline solution to partially loosen but not completely remove the encrusting substances associated with the fibre in the wood structure whereby the fibres are imperfectly retained in their natural arrangement, and shredding said wood to produce for the most part flexible bundles of fibres in such Iarrangement of substantial strength and capable of firmly felting together.

c 3. The process of producing an absorbent fibrie roduct from wood which is characterize ing substances associated with the wood fibres to provide increased capillarityof said encrusting substances partially retained between the fibres, and then mechanically shredding the wood to produce masses consisting for the most part of bundles of fibres bound by said modified substances in approx imate natural arrangement.-

4. The method of making fibre, which is characterized by cooking wood material with 4% to 14% of its weight of alkali to soften it, and shredding the same into a mass of bundles of fibres, in which mass the *fnajor portion of the bundles is in the form of flexible threads containing fibres in their natural relationship.

. 5. The process'of producing wood fibre consisting in steaming wood material, cooking the same under pressure at an elevated temperature with an alkali to partially disintegrate the encrustations, and shredding the remaining structure-into a mass of fibre bundles, in which mass the major portion of the bundles is in the form of flexible threads containing fibres in their natural relation- 6. The method of making felt which com- .prises cooking under pressure wood chips with 4% to 14% of their weight of alkali to soften them and incompletely release the bond between individual fibres, shredding the chips for the most part into flexiblefibre bundles and matting the same into sheets, the

fibre bundles containing the fibres for the most part in their natural relationship.

7. The method of aking dry felt which comprises chemically softening the bond between fibres of wood insufficiently to release the fibres from each other in their natural arrangement, separating the wood into bundles of said incompletely released fibres, and matting said bundles into sheets, the fibre bundles containing the fibres for the most part in their natural relationship.

8. The method of making felt which comprises cooking wood with weak sodium hydroxidesolutions, to weaken but not completely remove the; bond between the fibres,

, shredding the resulting fibrous material for the most part into fibre bundles of irregular size having the fibres therein retained in part at least intheir natural relation, and matting the same into sheets.

9. The process of making felt of predetermined permeability which consists in forming a felt stock by shredding into bundles of wood fibres wood treated chemiy chemically modifying the encrust felt is produced, and'controlling the permeability of the felt by mixing with the felt stock a quantity of short fibre which partially fills the voids between the bundles of the felt stock.

10. The process of making absorbent felt which is characterized by partially disintegrating ood by treatment with limited amounts 0 alkaline chemicals to incompletely loosen the encrusting substances so as to release fibre ends while maintaining the fibres bound in approximately natural relation, reducing the treated wood to shreds consisting of irregular bundles of fibres so bound, mixing theshreds with water and forming a wet felted web' from such shredded stock, and controllin the porosity of the felt web by the degree and duration of pressure on said web.

11. An intermediate wood product consisting of wood fibres and their natural bonding encrustations for the most part in the form of bundles of fibres, the encrustations being in a,

wood product comprising for the most part bundles of individual fibres substantially longer and stronger than the individual fibres, said fibres being held together in the bundles by the natural encrusting substances associated therewith substantially in their relation as in the wood structure, said encrusting substances being in a chemically partially disintegrated state whereby the fibre bundles are absorbent by reason of the capillary spaces provided by the partially disintegrated encrusting substances.

a 13. As anarticle vof manufacture, a shredded vegetable fibre suitable for felt comprising for the most part bundles of chemically treated wood fibre in which the individual fibres of the bundles substantially retain their natural positions in the bundles and are held together by a part of the encrusting submodified to soften the bundles, the pores or voids between the bundles in such felt structure being partially filled with other material to control the eflective size of the voids and the permeability of the felt structure. 15. As an article of manufacture, a flexible sheet of material possessing absorption properties composed of coniferous wood fibres disintegrated for the most part into masses 13 of long fibre bundles, and waste paper stock, felted together, said fibre bundles having the fibre encrusting substances chemically soft-e'ned but bonding the fibres in the bundles in substantially their natural arrangement.

16. As an article of manufacture, a sheet of absorbent felt composed of coniferous. wood disintegrated for the most part into bundles of the wood fibres, and ordinary rag felt fibres felted with the bundles of wood 23 fibres, said bundles of fibres having the natural bonding encrustation of the fibres chemically modified but retaining suflicient bond between the fibres to preserve substantially the arrangement of the fibres in the bundles.

:5 17. As an article of manufacture, a flexible sheet of fibrous material composed of wood disintegrated for the most part into bundles of fibres. in substantiallytheir naturalarrangement held together by their natural 5c bond chemically modified to increase the absorptive capacity of the bundles, said fibres being felted together to forin a porous sheet capable of absorbing at least-twice its own weight of a waterproofing or filling saturat- :25 ing material.

. In testimony whereof, I afiix my signature.

PHILIP W. CODWISE. 

